AZ-305 Design data storage solutions Practice Question
A company needs to store audit logs for 7 years to meet compliance requirements. The logs are generated at a high volume and must be cost-effective. They need to run occasional queries on recent logs (less than 30 days old) but rarely on older ones. Which Azure storage solution should they recommend?
⚠ Common exam trap
Candidates often choose Azure Log Analytics (Option D) because it is associated with logs, but they overlook its retention limits and high cost for long-term storage, failing to recognize that Azure Blob Storage with lifecycle management is the correct archival solution for compliance-driven retention.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Blob Storage with lifecycle management to Archive tier
Azure Blob Storage with lifecycle management to the Archive tier is the correct solution because it provides a cost-effective storage hierarchy for high-volume audit logs. Lifecycle management can automatically move logs from the Hot or Cool tier to the Archive tier after 30 days, aligning with the requirement to keep recent logs queryable while minimizing costs for older logs that are rarely accessed. The Archive tier offers the lowest storage cost, making it ideal for 7-year retention of audit data.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Azure Blob Storage with lifecycle management to Archive tier
Why this is correct
Azure Blob Storage is an object storage service designed to hold massive amounts of unstructured data, making it ideal for high-volume audit logs. Lifecycle management can automatically move blobs from Hot to Cool to Archive based on age or last-modification time, so after 7 years the logs reside in the Archive tier, which offers the lowest storage cost. The Archive tier provides acceptable retrieval latency (minutes to hours) for compliance access, and optional immutability policies prevent tampering.
- ✗
Azure SQL Database
Why it's wrong here
Azure SQL Database is a fully managed relational database service priced per vCore or DTU, optimized for transactional workloads with strong consistency and dynamic indexing. Storing seven years of high-volume audit logs there would require expensive SQL storage, ongoing compute costs, and schema/partition management, none of which are necessary for simple append-only archival. Although a database can technically hold log text, its cost per GB is far higher than object storage and it lacks automatic tiering to a low-cost archive tier.
- ✗
Azure Cosmos DB
Why it's wrong here
Azure Cosmos DB is a globally distributed, multi-model NoSQL database that provisions throughput in Request Units per second, incurring RU charges for every write even when logs are being appended. It is engineered for low-latency, transactionally consistent access across regions, not for infrequently queried archival data, and its storage cost per GB is an order of magnitude higher than Blob Storage. There is also no lifecycle-based transition to an Archive-class tier, so holding 7 years of logs would waste expensive throughput and storage resources.
- ✗
Azure Log Analytics
Why it's wrong here
Azure Log Analytics is the query and analysis engine for Azure Monitor, designed for operational insights over recent telemetry, and its interactive retention is limited to a maximum of 730 days. While data can be exported to storage, the service itself has no native Archive tier for cheap long-term retention, and keeping 7 years of audit logs in Log Analytics would incur significantly higher costs than Blob Storage. Thus it is not a suitable standalone solution for a 7-year compliance requirement.
Quick reference
Azure Blob Storage Tier Comparison
| Tier | Storage Cost | Retrieval Cost | Latency | Use Case |
|---|---|---|---|---|
| Hot | Highest | Lowest | Immediate | Active data, frequent reads |
| Cool | Lower | Higher | Immediate | Data accessed < once / month |
| Cold | Lower still | Higher | Immediate | Data accessed < once / quarter |
| Archive | Lowest | Highest + rehydration delay | Hours | Long-term compliance retention |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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